The present invention relates to a surface acoustic wave device and more particularly to a surface acoustic wave device using a type of transducer known as washboard transducer. The present invention also relates to a method of making the surface acoustic wave device.
Heretofore some surface acoustic wave devices use surface acoustic wave transducers which are metal electrodes shaped in a single phase grating pattern or in an interdigital grating pattern (see for example, U.S. Pat. No. 3,805,195, issued to Arthur Miller on Apr. 16, 1974). Transducers shaped in these patterns have limitation in use caused by the inherent design of these patterns. The frequency of a surface acoustic wave generated by a transducer shaped in a single phase grating pattern is limited by the spatial separation between pairs of adjacent electrodes. As the distance between adjacent electrodes decreases, the frequency of the surface acoustic wave generated by that transducer increases. However, difficulty had been encountered in constructing a single phase grating transducer with very small spatial separation between adjacent electrodes. Thus, one limitation imposed by the design of the single phase grating pattern, is the inability to generate high frequency surface acoustic waves.